/*
    This file is part of the substandard lisp implementation of Standard Lisp
    Copyright (C) 2011 Nicky Nickell

    substandard lisp is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

function std_cond(a, env) {
  var u = a[0];

  for (var i = 0; i < u.length; i++) {
    var antecedent = u[i].car;
    var consequent = u[i].cdr.car;

    if (antecedent.evaluate(env) != NIL) {
      return consequent.evaluate(env);
    }
  }

  return NIL;
}

/*---
name: cond
arity: 0
rest: true
ftype: FTYPE_FEXPR

argument-types:
  - TYPE_PAIR

doc: |
  explaining what cond is / how it is used!

tests: |
  (cond (T 1)) -> 1
  (cond (NIL 1)) -> NIL
  (cond (NIL 1) (T 2)) -> 2
  (cond (NIL 1) (NIL 1)) -> NIL
  (cond ((numberp 'a) 1) ((numberp 1) 2)) -> 2
  (cond (NIL 1) (T (plus 1 1))) -> 2
...*/
